Update multiple formatter interface

Closes #295.

features/config_formatters.feature

@@ -50,3 +50,28 @@ Feature:
     When I successfully run `bundle exec rake test`
     Then the output should contain "lib/faked_project/meta_magic.rb (coverage: 100.0%)"
     And the output should match /Formatter [^\s]* failed with RuntimeError: Unable to format/
+
+  Scenario: With multiple formatters
+    Given SimpleCov for Test/Unit is configured with:
+      """
+      require 'simplecov'
+      SimpleCov.formatters = [
+        SimpleCov::Formatter::SimpleFormatter,
+        Class.new do
+          def format(result)
+            raise "Unable to format"
+          end
+        end
+      ]
+
+      SimpleCov.at_exit do
+        puts SimpleCov.result.format!.join
+      end
+      SimpleCov.start do
+        add_group 'Libs', 'lib/faked_project/'
+      end
+      """
+
+    When I successfully run `bundle exec rake test`
+    Then the output should contain "lib/faked_project/meta_magic.rb (coverage: 100.0%)"
+    And the output should match /Formatter [^\s]* failed with RuntimeError: Unable to format/

lib/simplecov/configuration.rb

@@ -1,5 +1,6 @@
 require 'fileutils'
 require 'docile'
+require 'simplecov/formatter/multi_formatter'
 #
 # Bundles the configuration options used for SimpleCov. All methods
 # defined here are usable from SimpleCov directly. Please check out
@@ -74,6 +75,24 @@ def formatter(formatter=nil)
     @formatter
   end
 
+  #
+  # Sets the configured formatters.
+  #
+  def formatters=(formatters)
+    @formatter = SimpleCov::Formatter::MultiFormatter[*formatters]
+  end
+
+  #
+  # Gets the configured formatters.
+  #
+  def formatters
+    if @formatter.is_a?(SimpleCov::Formatter::MultiFormatter)
+      @formatter.formatters
+    else
+      Array(formatter)
+    end
+  end
+
   #
   # Certain code blocks (i.e. Ruby-implementation specific code) can be excluded from
   # the coverage metrics by wrapping it inside # :nocov: comment blocks. The nocov token

lib/simplecov/formatter/multi_formatter.rb

@@ -1,25 +1,28 @@
-class SimpleCov::Formatter::MultiFormatter
-  def self.[](*args)
-    Class.new(self) do
-      define_method :formatters do
-        @formatters ||= args
+module SimpleCov
+  module Formatter
+    class MultiFormatter
+      def self.[](*args)
+        Class.new(self) do
+          define_method :formatters do
+            @formatters ||= args
+          end
+        end
       end
-    end
-  end
 
-  def format(result)
-    formatters.map do |formatter|
-      begin
-        formatter.new.format(result)
-      rescue => e
-        STDERR.puts("Formatter #{formatter} failed with #{e.class}: #{e.message} (#{e.backtrace.first})")
-        nil
+      def format(result)
+        formatters.map do |formatter|
+          begin
+            formatter.new.format(result)
+          rescue => e
+            STDERR.puts("Formatter #{formatter} failed with #{e.class}: #{e.message} (#{e.backtrace.first})")
+            nil
+          end
+        end
       end
-    end
-  end
 
-  def formatters
-    @formatters ||= []
+      def formatters
+        @formatters ||= []
+      end
+    end
   end
-
 end

lib/simplecov/formatter/simple_formatter.rb

@@ -1,19 +1,23 @@
 #
 # A ridiculously simple formatter for SimpleCov results.
 #
-class SimpleCov::Formatter::SimpleFormatter
-  # Takes a SimpleCov::Result and generates a string out of it
-  def format(result)
-    output = ""
-    result.groups.each do |name, files|
-      output << "Group: #{name}\n"
-      output << "="*40
-      output << "\n"
-      files.each do |file|
-        output << "#{file.filename} (coverage: #{file.covered_percent.round(2)}%)\n"
+module SimpleCov
+  module Formatter
+    class SimpleFormatter
+      # Takes a SimpleCov::Result and generates a string out of it
+      def format(result)
+        output = ""
+        result.groups.each do |name, files|
+          output << "Group: #{name}\n"
+          output << "="*40
+          output << "\n"
+          files.each do |file|
+            output << "#{file.filename} (coverage: #{file.covered_percent.round(2)}%)\n"
+          end
+          output << "\n"
+        end
+        output
       end
-      output << "\n"
     end
-    output
   end
 end